The best way to understand something in the spiritual world is by studying its counterpart in the physical world.
To get a true education, going to school is not enough. School helps students gain knowledge; however, true education is in gaining wisdom, which can only be earned with experience.
Thus far, the only people who can grant you immortality are not scientists, but writers. By writing you into their books, they may not only immortalize you, but also grant you superpowers.
Without wisdom, a teacher is nothing more than a research paper: a knowledge filled text which is boring and has no practical use. With wisdom, a teacher is like a great novel: a text filled with knowledge, practical applications and, above all, fun.
Anyone can put a price on knowledge - schools and universities do it all the time, but no one can put a price on wisdom for it can neither be bought nor sold. It should be given and accepted with no ulterior motives.
There is no real distinction between who can and cannot be a teacher. All that matters is that this person should have knowledge of the subject matter, empathy and compassion with others, and, above all, a great sense of humor which is the true mark of wisdom.